Amplifying Photon Upconversion in Alloyed Nanoparticles for a Near-Infrared Photodetector.

Yan, Long; Tao, Lili; Zhang, Qizheng; Huang, Haozhang; Zhang, Qinyuan; Zhou, Bo · Nano Lett · 2024

basic_science · Level V

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Abstract

Photon upconverison has attracted a substantial amount of interest in diverse fields due to its characteristic anti-Stokes emissions. However, obtaining intense emission under low-power laser irradiation has remained a challenge. Here we report a mechanistic design of activator-sensitizer alloyed nanoparticles to achieve bright upconversion under weak infrared irradiation. This design allows a nearest sensitizer-activator separation to facilitate efficient energy transfer that results in remarkably enhanced upconversion (>2 orders of magnitude) under 0.26 W cm<sup>-2</sup> irradiation compared to that of the Er sublattice, and the upconversion quantum yield also shows a 20-fold increase. Interestingly, the alloyed nanoparticles exhibit a gradual change in emission color with an increase in Yb<sup>3+</sup> content, and moreover, their emission colors can be dynamically controlled by simply modulating the excitation laser power and pulse widths. Such alloyed nanoparticles show great promise for application in a near-infrared photodetector.